From: Eric Dumazet <edumazet@google.com>
Date: Tue, 10 Dec 2024 18:33:52 +0000 (+0000)
Subject: ipv6: mcast: annotate data-race around psf->sf_count[MCAST_XXX]
X-Git-Tag: v6.14-rc1~162^2~237^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=00bf2032e97691c4b53427b33a85b134324e2a94;p=thirdparty%2Flinux.git

ipv6: mcast: annotate data-race around psf->sf_count[MCAST_XXX]

psf->sf_count[MCAST_XXX] fields are read locklessly from
ipv6_chk_mcast_addr() and igmp6_mcf_seq_show().

Add READ_ONCE() and WRITE_ONCE() annotations accordingly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241210183352.86530-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 09622142b0705..5ca8692d565d5 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1037,8 +1037,8 @@ bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
 				break;
 		}
 		if (psf)
-			rv = psf->sf_count[MCAST_INCLUDE] ||
-				psf->sf_count[MCAST_EXCLUDE] !=
+			rv = READ_ONCE(psf->sf_count[MCAST_INCLUDE]) ||
+				READ_ONCE(psf->sf_count[MCAST_EXCLUDE]) !=
 				READ_ONCE(mc->mca_sfcount[MCAST_EXCLUDE]);
 		else
 			rv = READ_ONCE(mc->mca_sfcount[MCAST_EXCLUDE]) != 0;
@@ -2287,7 +2287,7 @@ static int ip6_mc_del1_src(struct ifmcaddr6 *pmc, int sfmode,
 		/* source filter not found, or count wrong =>  bug */
 		return -ESRCH;
 	}
-	psf->sf_count[sfmode]--;
+	WRITE_ONCE(psf->sf_count[sfmode], psf->sf_count[sfmode] - 1);
 	if (!psf->sf_count[MCAST_INCLUDE] && !psf->sf_count[MCAST_EXCLUDE]) {
 		struct inet6_dev *idev = pmc->idev;
 
@@ -2393,7 +2393,7 @@ static int ip6_mc_add1_src(struct ifmcaddr6 *pmc, int sfmode,
 			rcu_assign_pointer(pmc->mca_sources, psf);
 		}
 	}
-	psf->sf_count[sfmode]++;
+	WRITE_ONCE(psf->sf_count[sfmode], psf->sf_count[sfmode] + 1);
 	return 0;
 }
 
@@ -3079,8 +3079,8 @@ static int igmp6_mcf_seq_show(struct seq_file *seq, void *v)
 			   state->dev->ifindex, state->dev->name,
 			   &state->im->mca_addr,
 			   &psf->sf_addr,
-			   psf->sf_count[MCAST_INCLUDE],
-			   psf->sf_count[MCAST_EXCLUDE]);
+			   READ_ONCE(psf->sf_count[MCAST_INCLUDE]),
+			   READ_ONCE(psf->sf_count[MCAST_EXCLUDE]));
 	}
 	return 0;
 }